Lab-Grown Blood Vessels Offer New Hope for Trauma Patients

In the United States, approximately 185,000 amputations are performed annually, with nearly half attributed to severe injuries to blood vessels that disrupt circulation. While surgeons can transplant veins from other parts of a patient's body to prevent amputation, not all patients have suitable veins, presenting a significant challenge in trauma care.

A groundbreaking advancement in tissue engineering has emerged with the recent approval of a bioengineered blood vessel by the Food and Drug Administration (FDA). This innovation, developed by Humacyte, a biotechnology company based in North Carolina, aims to restore blood flow in patients suffering from traumatic injuries, including those caused by gunshots, vehicular accidents, industrial incidents, and combat.

According to experts, some patients endure such severe injuries that they lack available veins for transplantation. Even in cases where veins are present, they are often inadequate substitutes for arteries due to their structural weaknesses.

The journey to developing a viable engineered blood vessel began in the 1990s when the founder of Humacyte recognized the need for a better solution while training as a physician. Witnessing the invasive process of searching for suitable blood vessels during heart bypass surgeries sparked her interest in creating alternative options.

Starting with blood vessels grown in laboratories from a few cells taken from pig arteries, initial animal tests demonstrated their functionality. This success paved the way for extensive research and development, leading to the isolation of blood vessel cells from human organ and tissue donors. After testing cells from over 700 donors, the team identified five donors whose cells were particularly effective in growing and expanding in laboratory conditions.

Currently, Humacyte has a sufficient bank of cells from these five donors to produce between 500,000 and 1 million engineered blood vessels. The manufacturing process involves creating batches of 200 vessels using custom-designed biodegradable polymer scaffolds, which are 42 centimeters long and 6 millimeters thick. These scaffolds are seeded with millions of donor cells and placed in nutrient-rich incubators for approximately two months to promote tissue growth. During this period, the cells secrete collagen and other proteins that contribute to the structural integrity of the developing tissue. Eventually, the scaffolds dissolve, leaving behind a de-cellularized and flexible tissue that mimics a natural blood vessel.

This engineered tissue is devoid of living human cells, significantly reducing the risk of rejection when implanted in patients. Experts in the field have noted that previous attempts to create similar tubular materials have faced challenges, making this development noteworthy.

Traditional synthetic alternatives, such as those made from Teflon or polyester (Dacron), are sometimes utilized when suitable blood vessels are unavailable. However, these materials can increase the risk of infection, as bacteria tend to thrive on foreign substances in the body.

Clinical trials assessing the safety and efficacy of the engineered blood vessel involved 51 civilian patients and 16 military patients with traumatic injuries. The results showed that nearly 92 percent of the bioengineered vessels remained patent and functional 30 days post-implantation, compared to 79 percent for synthetic grafts. Furthermore, the amputation rate among patients receiving the engineered vessels was approximately 4.5 percent, significantly lower than the 24 percent observed in studies of synthetic grafts. The infection rate for the bioengineered vessels was less than 1 percent, while over 8 percent of synthetic options experienced infections.

This innovative approach allows the patient's body to integrate with the engineered vessel, promoting the growth of its own cells into the vessel wall, thereby functioning similarly to a natural blood vessel. While the current FDA approval permits the use of these vessels solely for trauma patients, Humacyte is exploring additional applications, including in kidney dialysis and treatments for peripheral artery disease.

Early tests in non-human primates have shown promise for using smaller versions of the engineered vessels in heart bypass procedures. Experts in the field have lauded this development as a remarkable achievement in medical science, highlighting its potential to transform future medical practices.